Combustion inside the engine

A modeling study is applied on methane HCCI process of micro power device.

Mathematical formulas are established to predict the combustion characteristics.

Impacts of catalysis on the combustion characteristics are analyzed respectively.

The catalyst can improve the work steadily and reliability of micro power device.

In order to investigate the catalytic combustion characteristics concerning homogeneous charge compression ignition (HCCI) in micro power device, numerical simulations with a 3D computation model that coupled motion of free piston and fluid dynamics of methane–air mixture flow were carried out and detailed gas-phase and surface catalytic reaction mechanisms of methane–air mixture were applied to the catalytic reactions model, a series of mathematical formula are established to predict the characteristics of compression ignition condition, impacts of catalysis on temperature, pressure, work capacity and other factors were analyzed respectively. Simulation results reveal that catalytic combustion facilitates the improvement of energy conversion efficiency and extends the ignition limit of methane–air mixture obviously, the ignition timing is brought forward as well, while compression ratio decreases and ignition delay period shrinks significantly. Numerical results demonstrate that the existence of catalytic wall helped to restrain the peak combustion pressure and maximum rate of pressure rise contributing to the steadily and reliability of operation inside micro free-piston power device.

Keywords

• Micro power device;
• Free-piston;
• HCCI;
• Catalytic combustion;
• Combustion steadily;
• Combustion reliability